1. Field of the Invention
The present invention relates to a method and apparatus for controlling a disk drive, and more particularly, to a method and apparatus for controlling the movement of a transducer in a disk drive to optimize a lube layer coated on a disk.
This application claims the benefit of Korean Patent Application No. 10-2006-0012878, filed on Feb. 10, 2006, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
2. Discussion of Related Art
A hard disk drive (HDD) reproduces data recorded on a disk or records data on the disk using a transducer (a head). Bits per inch (BPI) is the write density of a disk in the rotational direction. Tracks per inch (TPI) is the write density of a disk in a radius direction. As BPI and TPI have increased, small-sized and high storage capacity HDDs are manufactured and a more accurate positional mechanism is required.
To prevent damage due to friction between the disk and the head of the HDD, a lube layer is coated on the disk. However, when the disk rotates at high speed while the head is located above the lube layer on the disk, the lube coated on the disk is moved aside due to air pressure and friction generated between the head and the disk due to the up and down floating motion of the head. Since movement of the lube on the disk is small this does not evolve into a serious problem. However, if the head stays in a specific position above the disk without moving for a significant length of time, or if the head moves a short distance for a relatively long time, the lube which is moved aside increases. Accordingly, the thickness of the lube at and around the head position becomes gradually thinner which obstructs the movement of the head, thereby leading to possible damage of the head and/or the disk.
A technique for solving this problem is disclosed in commonly assigned Korean Patent Application No. 1990-12208 entitled “Method of Controlling Actuator in HDD,” (“the '208 Application”). The '208 Application discloses a technique of moving a disk head by driving an actuator after a predetermined period of time if an HDD is not accessed within the predetermined time. This approach prevents possible damage due to friction between the head and the disk by periodically moving the head only in an idle state in which a read/write command is not received from a host device for a predetermined time. However, if the host device transmits consecutive read/write commands for reading/writing data at the same position on the disk, the conventional approach cannot prevent damages due to friction between the head and the disk because of the accumulated lube in that disk location. In addition, if a pattern of host commands, such as a sequential read/write command, requires the head to be moved bit-by-bit in one direction, the head moves and accumulates the lube in one direction, ultimately affecting a track following operation of the head.